Recently, LEDs have been more widely used as light sources throughout the industry including lighting devices. Thus, researches are actively carried out in each industrial field so as to use LEDs effectively and efficiently.
In particular, researches for LED lamps as new lamps in a concept of replacing traditional lamps have come to greatest prominence.
However, LED-related companies and markets lack basic knowledge of traditional lamps and actual approaches thereof do not fulfill the expectations. In particular, in the price range which is put first in the market, the price of LED lamps is very high to the extent that LED lamps cost five times to twenty times as much as traditional lamps. Thus, in practice, the LED lamps are very inadequate as a replacement for the traditional lighting sources.
For example, a Multifaceted Reflector (MR) lamp of a halogen lamp, which is a kind of traditional lamp, has a form and configuration in which a reflective material is uniformly coated on respective facets on a reflecting plate surface of a pressed glass having a polyhedron structure and the respective facets exhibit a characteristic of optically collecting or concentrating light emitted from a filament. Some MR lamps have a smooth structure rather than a polyhedron structure but yet, are collectively called “MR lamp” or “MR 16” (here, the number 16 indicates the largest diameter size of the MR lamp).
Such MR lamps were originally developed for use as a light source of a slide projector. At present, the MR lamps are widely used for direct lighting, such as indoor lighting of department stores, hotels, restaurants, or the like, or for display lighting.
However, there is an inconvenience in that attention should be paid always when using such an MR lamp which is a kind of traditional lamp since a dangerous situation may occur when the MR lamp is not normally used.
Specifically, the temperature of the filament increases to at least 260° C. and a halogen regeneration cycle is executed during lighting-up. Thus, there is danger of burns due to the high temperature and attention should be paid when handling an object which may be damaged by heat. When the heated filament lamp surface is touched by hand, the lamp may be destroyed. Further, since the MR lamp is not a light source with high efficiency like a fluorescent light, there is a limit in that the MR lamp is not suitable for an application for entire lighting but only for localized lighting.
In order to overcome the above-mentioned disadvantages of the existing MR lamps and enhance efficiency, the LED lamps for use in MR lamp replacement, which include a chip type LED module (LED package), are proposed in the forms as illustrated FIGS. 1a and 1b. Most of the LED lamps include a chip type LED package, a heat sink, and a socket.
Here, as illustrated in FIG. 1a, a lens unit having a plurality of lenses, of which the number corresponds to the number of LED chips of the LED module in a one-to-one relationship, may be provided, or in some cases, a transparent or translucent cover may be provided instead of the lens unit.
In addition, in order to improve efficiency, the LED lamps may further include a reflector configured to control divergent light of the LED chips.
Here, in order to replace an existing 50 W MR lamp, a chip type LED package with 8 W to 10 W power is used, and in order to replace an existing 20 W MR lamp, a chip type LED package with a 4 W to 5 W power is used.
However, the LED lamps conventionally proposed for use in MR lamp replacement have a problem in that the energy efficiency and lighting efficiency are not so high compared to the existing MR lamps. When the power of the LED packages is increased in order to solve this problem, the efficiency of the LED packages may be improved. However, this newly causes problems of increasing the price. In addition, there is also a problem in that the sizes of the LED lamps as well as the sizes of the LED packages are increased. Further, there is an inconvenience in that a problem of heat dissipation caused by the size increase should be solved.
In addition, an LED package in which a plurality of chips is arranged at an interval basically has an unstable chip arrangement due to discontinuous chip mounting. Due to this, the LED package unavoidably has an incomplete lighting characteristic. This will cause a problem of locally deforming color coordinates, generating a color separation phenomenon. In particular, there is a problem in that, as illustrated in FIG. 9b, a yellow pattern such as a yellow stripe and a black portion are formed on a light radiation surface.
Furthermore, in the LED lamps conventionally proposed for use in MR lamp replacement, the yellow pattern is not removed even though a reflector and/or a cover are provided. Thus, an improvement in terms of efficiency is requested and a product which may be implemented at a low cost is demanded.